Conventionally, as one of methods for producing concrete products, a centrifugal casting method is known and the machine used for the method comprises a rotary drum which is rotated at a high speed by a rotating mechanism and a multiplicity of outer frames and a multiplicity of cores which are mounted on the inner surface of the rotary drum.
For producing the concrete products, concrete slurry is charged into the rotary drum by way of a feeder chute or a screw feeder which has the front end thereof disposed within the rotary drum while the rotary drum is being rotated at a high speed. Due to the above rotation of the rotary drum, a centrifugal force is exerted on the charged cement slurry and the cement slurry fills a plurality of casting spaces defined by the outer frame and cores. After the above casting operation, the cement slurry filled in the casting space is hardened and cured for a desired period and concrete products are removed from the casting spaces.
With the above centrifugal casting machine, however, in each casting operation, the outer frames and the cores must be mounted on the inner surface of the rotary drum before the casting operation, and the outer frames and the cores must be dismounted from the inner surface of the rotary drum to remove the concrete products from the rotary drum after the casting operation. Accordingly, the casting operation is, in general, very cumbersome and time-consuming.
Furthermore, during the casting operation, the concrete slurry is filled in the casting spaces with a considerable centrifugal force so that the concrete products, after being hardened, firmly adhere to the inner surfaces of the outer frames or outer surfaces of the cores. Accordingly, during the dismounting of the outer frames or the cores to take out the concrete products from the rotary drum, the concrete products receive a biased force which causes the rupture or cracks on the concrete products.
Accordingly, it is an object of the present invention to provide a casting frame structure of a centrifugal casting machine which can resolve the above defects of conventional casting frame structures so as to enable the prompt or ready mass-production of the concrete products.
It is another object of the present invention to provide a casting frame structure of a centrifugal casting machine which can produce the concrete products of high quality and high precision which are completely free from ruptures or cracks.